IMPROVED HEAT TRANSFER TUBE WITH GROOVED INNER SURFACE

摘要

The inner surface of the tube (10) has a primary set of fins (12)and an intermediate sets of fins (26) positioned in the areas (24) between the primary fins (12) and at an angle relative to the primary fins (12). In a preferred embodiment of the inner surface tube design, the intermediate fins (26) are positioned relative to the primary fins (12) to result in a grid-li ke appearance. A first set of rollers creates the primary (12) and intermediate fin (26) designs on at least one side of a board. A second set of rollers ma y be used to further enhance the performance. After the desired pattern has be en transferred onto the board with the rollers, the board is then formed and welded into a tube, so that, at a minimum, the inner surface design of the resulting tube includes the intermediate fins as contemplated by the present invention.